Methodology for the chemical and mechanical treatment and cleanup of oily soils, drill cuttings, refinery wastes, tank bottoms, and lagoons/pits

ABSTRACT

This invention relates to an improved methodology for the removal of oily hydrocarbon materials sorbed onto the surface(s) of inorganic materials. Said oily hydrocarbon materials may be partially oxidized or may be unoxidized. The invention makes use of an exothermic chemical reaction involving hydrogen peroxide and alkaline agents and hydrocarbons to partially oxidize certain reactive functional groups on the hydrocarbons and thus rendering said hydrocarbons more water soluble thereby facilitating the separation of the sorbed or free product hydrocarbons from both the surface of the inorganic material and also from between the interstitial grains (porosity). Furthermore the exothermic process facilitates the reduction of viscosity of said hydrocarbons thus further facilitating the separation of the hydrocarbons from the aqueous and inorganic phases. Said separation can be further enhanced by standard separation techniques such as settling, centrifugation, decantation, use of cyclones, and any and all other physical separation processes. Further by utilizing the hydrogen peroxide in an alkaline environment the interfacial tension of the oil is reduced further aiding said hydrocarbon-water-inorganic sediment separation and recovery of the hydrocarbons.

CROSS-REFERENCE TO RELATED APPLICATIONS

U.S. PROVISIONAL APPLICATION No. 61/068,412

REFERENCES CITED

None

Within the exploration, transportation, processing, and refining segments of the oil business (and other businesses), a consistently re-occurring problem exists related to waste minimization and/or cleanups of oily materials. Specifically production tanks can become partially filled with oily sediments and dirt, crude oil spills around production facilities are common requiring significant cleanup costs. In and around refineries storage tanks must be cleaned on a regular basis. These “tank bottoms” (as known in the industry) typically consist of a mixture of oil, water, salty water, clays and sand sized materials and bacteria. These items often are present as an emulsion-which is very difficult to break. Hence recovery of the entrained oil and separation of the solids under a waste minimization approach is hampered. Another source of material requiring waste minimization around refineries is API separator sludge. Again this material contains oil, salty to fresh water, bacteria, inorganic material such as dirt, clays, fine grained sand, rust, and other items. The API separator sludge also can exist as an emulsion which hampers the processing/waste minimization efforts thus resulting in costly disposal options. Another source of oilfield related wastes are storage pits, ponds, lagoons associated with production operations. Typically these pits, ponds and/or lagoons contain material similar to the previously described tank bottoms and/or API separator and thus inhibit cleanup of the pits, etc. Another source of material requiring cleanup and waste minimization is drill cuttings. Drill cuttings result from the drilling operations for oil wells. Oftentimes the drill cuttings contain oil, drilling mud additives, salty water and/or fresh water, crushed and groundup rock of varied lithology, and emulsions. The disposal of drill cuttings is difficult and expensive since the drilling mud additives and the oil typically are adsorbed onto the rock particles-thus requiring special-and expensive-disposal options. Another source of oilfield related wastes are oil spills on the native soil and/or ground that contaminates the soil and requires cleanup.

Ideally a simple, safe and inexpensive process for the treatment of all the above items would benefit the waste minimization and resource recovery of the entrained oil. In addition the process should be applicable with minimal energy requirements to aid operation in remote locations.

DESCRIPTION OF THE INVENTION

A process to treat the above oily waste products to achieve separation and recovery of the salty or fresh water, the oil, and the rock and/or dirt materials and thereby achieve waste minimization has been developed and tested. Furthermore this said process can break emulsions, and more importantly is an exothermic (heat generating) process that minimizes the need for external heat sources. The entrained oil can be recovered as a valuable product, whereas the soil and/or rock material can be effectively cleaned of the adsorbed oil which therefore allows a multitude of inexpensive disposal options for the solids. The entrained water can be further processed if so desired to cleanup to disposal standards applicable to different locales. Alternately the entrained water may be reused as process water for subsequent treatment having the advantage of utilization of the residual treatment chemicals (such as alkaline agents) in the water.

The process developed entails the following steps for emulsions and/or free liquid streams of oily material:

-   -   1. pH adjustment to >9.0 preferably with CaO or Ca(OH)2, but in         certain instances other alkaline agents may be beneficially         utilized for compatibility reasons with said material to be         treated;     -   2. addition of hydrogen peroxide (H2O2) preferably having a         concentration greater than about 10% and in amounts equal to         0.5%, or greater, of the feed weight of the material to be         processed;     -   3. monitoring of the pH and temperature     -   4. addition of additional alkaline agents and/or peroxide to         achieve a temperature rise of the mixture of a minimum of 15         degrees centigrade;     -   5. mixing of the material by any appropriate manner or means;     -   6. settling of the mixture;     -   7. separation of the recovered oil and water by any means such         as a clarifier and/or oil water separator;     -   8. separation of the cleaned soil, rock, dirt by any means such         as a clarifier or centrifuge;     -   9. final disposal of the cleaned soil, rock, dirt in an         appropriate manner.

The process can be operated in either a batch or continuous mode using standard tanks, or other suitable vessels.

Chemical reactions are:

CnH2n+2+H2O2=nCO2+H2O+heat   1.

CnH2n+2+CaO+HOH=(CnH2n+1)−1+Ca(OH)2+(H+)+heat   2.

The use of alkaline agents for removal of oily substrates from inorganic materials is well known process. The use of peroxide to achieve partial oxidation of organic material, and thus render it more water soluble, is also well known. However the combination of the two processes to achieve lower cost cleanup of tank bottoms, drill cuttings, API separator sludges, oily pits/lagoons, and especially for the breaking of oil/water emulsions, has not previously been practiced nor discovered.

Bench scale laboratory testing of this process has already demonstrated the efficacy of the process. 

1. A chemical and physical method to remove oily materials from sand, silt, grit, soil, sediments by the use of an exothermic process using hydrogen peroxide operating under alkaline conditions to liberate the oily and/or hydrocarbon material away from the surface of inorganic materials and thus allow for the separation of the hydrocarbons, water, and inorganic constituents.
 2. A method to remove the liberated hydrocarbons and achieve separation of said hydrocarbons that now exist in both the aqueous phase and/or as a free phase by means of settling, decantation, filtering, centrifugation, and any other method commonly employed to achieve oil, water, solids separation.
 3. A method to raise the temperature of an oily substrate to achieve lower viscosity of said hydrocarbon.
 4. A method to modify the hydrocarbon chemistry to allow chemically reactive groups to form on said hydrocarbons and thus aid in the removal and separation of the hydrocarbons from the inorganic substrate.
 5. A method to decrease the interfacial tension between the hydrocarbon and water to facilitate the separation of the hydrocarbon from the water and from the inorganic sediment materials. 